Reidy Michael, Sharma Ruchika, Masison Daniel C
Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA.
Eukaryot Cell. 2013 May;12(5):739-45. doi: 10.1128/EC.00301-12. Epub 2013 Mar 15.
Hsp100 chaperones protect microorganisms and plants from environmental stress by cooperating with Hsp70 and its nucleotide exchange factor (NEF) and Hsp40 cochaperones to resolubilize proteins from aggregates. The Saccharomyces cerevisiae Hsp104 (Sc-Hsp104)-based disaggregation machinery also is essential for replication of amyloid-based prions. Escherichia coli ClpB can substitute for Hsp104 to propagate [PSI(+)] prions in yeast, but only if E. coli DnaK and GrpE (Hsp70 and NEF) are coexpressed. Here, we tested if the reported inability of Schizosaccharomyces pombe Hsp104 (Sp-Hsp104) to support [PSI(+)] propagation was due to similar species-specific chaperone requirements and find that Sp-Hsp104 alone supported propagation of three different yeast prions. Sp-Hsp70 and Sp-Fes1p (NEF) likewise functioned in place of their Sa. cerevisiae counterparts. Thus, chaperones of these long-diverged species possess conserved activities that function in processes essential for both cell growth and prion propagation, suggesting Sc. pombe can propagate its own prions. We show that curing by Hsp104 overexpression and inactivation can be distinguished and confirm the observation that, unlike Sc-Hsp104, Sp-Hsp104 cannot cure yeast of [PSI(+)] when it is overexpressed. These results are consistent with a view that mechanisms underlying prion replication and elimination are distinct.
热休克蛋白100（Hsp100）伴侣蛋白通过与热休克蛋白70（Hsp70）及其核苷酸交换因子（NEF）以及热休克蛋白40（Hsp40）共伴侣蛋白协同作用，将聚集的蛋白质重新溶解，从而保护微生物和植物免受环境压力。基于酿酒酵母热休克蛋白104（Sc-Hsp104）的解聚机制对于基于淀粉样蛋白的朊病毒复制也至关重要。大肠杆菌ClpB可以替代Hsp104在酵母中传播[PSI(+)]朊病毒，但前提是要共表达大肠杆菌DnaK和GrpE（Hsp70和NEF）。在这里，我们测试了粟酒裂殖酵母热休克蛋白104（Sp-Hsp104）无法支持[PSI(+)]传播是否是由于类似的物种特异性伴侣蛋白需求，并发现单独的Sp-Hsp104就能支持三种不同酵母朊病毒的传播。同样，Sp-Hsp70和Sp-Fes1p（NEF）也能替代它们在酿酒酵母中的对应物发挥作用。因此，这些长期分化物种的伴侣蛋白具有保守的活性，在细胞生长和朊病毒传播所必需的过程中发挥作用，这表明粟酒裂殖酵母可以传播自身的朊病毒。我们表明，可以区分热休克蛋白104过表达和失活导致的治愈情况，并证实了以下观察结果：与Sc-Hsp104不同，Sp-Hsp104过表达时无法治愈酵母中的[PSI(+)]。这些结果与朊病毒复制和消除的潜在机制不同的观点一致。
